The two streams meet at a confluence. It takes many tributary streams to form a river. A river grows larger as it collects water from more tributaries. Streams usually form rivers in the higher elevations of mountains and hills. The areas of depression between hills or mountains are known as valleys.
The world's fastest production single piston engine aircraft produced in Great Britain, deployed from 1945 to 1953. Heavily Modified Sea Fury aircraft can be seen today as air racers. Heinkel He-162 562 mph. Arguably the fastest WW II jet fighter.
The fastest aircraft (with wings) made by far is the space shuttle. . . . It travels at speeds in excess of mach 12. . . But the aircraft made with air breathing engines is the Bell X 41 based on SCRAM jet propulsion. , . It reached speeds of mach 7, . The fastest aircraft which used a Jet engine coupled with a RAM jet is the SR 71 Black Bird. . . .